The quantitative calculation and evaluation for soil and water conservation schemes of 106 expressways are made using soil and water loss impact index(SWII). The weight of each indicator is calculated by consulting experts about the weights of 9 indicators and applying analytic hierarchy process(AHP). The key factors for soil and water loss in different eroded areas are then analyzed by applying principal components analysis(PCA). According to the calculated SWII, the expressway projects can be divided into three types: high-influencing project with a value of SWII higher than 0.387, medium-influencing project with a value of SWII between 0.258 and 0.387, and low-influencing project with a value of SWII lower than 0.258. Based on the influencing degree of soil and water loss on expressway projects, some technical requirements are presented from the aspects of prevention criteria, engineering grades, allocating requirements of soil and water conservation measures and construction techniques.